1. Field of the Invention:
The present invention relates to a conduit coupling and particularly to a union conduit coupling wherein the union nut is adapted to be fitted over the free end of the conduit coupling body.
2. Description of the Prior Art:
The typical union coupling includes a larger diameter portion on the free extremity of the conduit body. The female union nut is slipped over the opposite end of the conduit body until the flange of the nut engages the enlarged portion of the conduit body extemity. The nut is then retained on the coupling body, but is free to rotate for connection with a male fitting or the like. In many instances it is not practical to mount the union nut onto the coupling body from the end opposite its free end. Accordingly, the prior art teaches a conduit body having a groove adapted to receive a C-shape clip for engagement with the nut flange to retain the nut in position. With this arrangement the nut is slipped over the free end of the coupling body, the clip is installed in the groove, and the coupling is ready for use. This system has a number of shortcomings, particularly the requirement that the exterior of the coupling body inwardly of its free extremity must be free of any connections, walls, or other obstructions which would prevent the full length of the union nut from passing inwardly on the coupling body sufficiently to place the clip in position in the coupling groove.
The prior art is also deficient in providing a means for quickly and easily bleeding off or pressure venting conduits, conduit couplings and the like. Typically a T-shape coupling or the like is interposed in the conduit to be vented and a petcock or similar small valve is used to selectively vent off gases or liquids or relieve excessive pressures. This arrangement is relatively expensive, requires extra fittings and presents an awkward or unslightly protusion from the body of the conduit.
Another form of venting arrangement is the provision of spaced O-rings in grooves of a conduit, with a longitudinally slidable sleeve carried on the O-rings and slidable to uncover a vent opening through the wall of the conduit between the pair of O-rings. In this arrangement an O-ring tends to be pinched and rolled out of its groove, possibly even being blown out of the groove by escaping pressure. Various other means for venting internal conduit pressures are shown in the prior art, but usually they are relatively expensive and incapable of directing the vented gas or fluid in a predetermined direction.
A need for an improved venting arrangement exists particularly in replacing service "exchange tanks" for water treatment such as deionization treatment. Residual pressure in the tank must be vented in order to minimize water spillage during the tank exchange, and air that is always entrapped in the top of a freshly installed tank should preferably be vented for efficient operation of the tank. Venting is also desirable to avoid the sudden escape of pressurized air and water mixtures the next time the tank is exchanged. Both safety and convenience considerations are involved.